Square root extraction signals are used to simplify closed pipe liquid or gas flow calculations and to improve resolution of the non-linear signal when converted to a flow reading.
The output from a Modbus 12 bit count can be transformed in the following ways:
A linear digital output signal of 0 to 4096 steps can be converted to a non-linear sq rt extraction by applying the following formula or table:
Advantages and Disadvantages of using a 4 to 20 mA Signal
A 4-20mA current signal has become very popular for many applications beyond it's original intended purpose in the process industry. It is now used throughout industry as the preferred measurement and control signal for many different types of systems.
Despite the popularity of the 4-20mA signal, it is not the best solution for every application and here are some of the 'for' and 'against' reasons for determining whether it is the right type of signal for your application.
Despite the popularity of the 4-20mA signal, it is not the best solution for every application and here are some of the 'for' and 'against' reasons for determining whether it is the right type of signal for your application.
How to Quickly find a Manufacturer's PDF Product Data Sheet
A pdf (Public Document Format) file is the most reliable and authoritive document to find if you are looking to view the manufacturer's specification for a particular product.
A pdf document has become the De facto standard for the majority of manufacturer's marketing departments because it enables them to better control the distribution of the published specification for their product. The pdf file format is not easily editable, the content is always rendered the same way no matter what device it is viewed on and most computer users can open the files with free to download reader software such as Adobe Reader.
A pdf document has become the De facto standard for the majority of manufacturer's marketing departments because it enables them to better control the distribution of the published specification for their product. The pdf file format is not easily editable, the content is always rendered the same way no matter what device it is viewed on and most computer users can open the files with free to download reader software such as Adobe Reader.
Why do Pressure Calibration Certificates show Rising and Falling Results?
When looking at a calibration certificate you will notice that the calibration points are set out in the order they were recorded as one set of rising results followed by a set of falling results.
The majority of pressure measurement equipment relies on the flexing of a mechanical component such as a metal diaphragm or a Bourdon Tube to sense a change in pressure. If you compare increasing pressure points to decreasing pressure points you will discover that the readings do not match exactly. This is due to Mechanical Hysteresis and the amount of error will vary depending on the amplitude of the cycle of pressure.
The majority of pressure measurement equipment relies on the flexing of a mechanical component such as a metal diaphragm or a Bourdon Tube to sense a change in pressure. If you compare increasing pressure points to decreasing pressure points you will discover that the readings do not match exactly. This is due to Mechanical Hysteresis and the amount of error will vary depending on the amplitude of the cycle of pressure.
Not Reading Zero when Pressure is Vented to Atmosphere
It is not unusual for a pressure measurement device to read slightly above or below zero with no pressure applied. The zero offset tolerance for a device is often incorporated into the accuracy statement or shown as a separate spec on the product data sheet.
When a gauge reference pressure instrument is first installed it should read very close to zero when measuring ambient air pressure. Some devices such as analogue output sensor, may have a small zero offset because it does not have sufficient fine adjustment to set the zero reading exactly. If there is a zero offset at zero pressure on a new device, it should be relatively small compared to the full measurement range.
When a gauge reference pressure instrument is first installed it should read very close to zero when measuring ambient air pressure. Some devices such as analogue output sensor, may have a small zero offset because it does not have sufficient fine adjustment to set the zero reading exactly. If there is a zero offset at zero pressure on a new device, it should be relatively small compared to the full measurement range.
What is a mV/V Output Sensitivity?
It is an electrical signal which is proportional to the applied excitation voltage and is also referred to as a ratio-metric or strain gauge output.
This type of output signal is produced by a wheatstone bridge strain gauge transducer which converts imbalance in bridge resistance generated by an applied force / load to a voltage drop between two opposite corners of the Wheatstone bridge circuit.
For a given fixed force, load or pressure, the voltage drop across two opposite corners of the circuit will is linearly proportional to the voltage supplied between the other two corners of the circuit. In a circuit diagram the wheatstone bridge is usually shown as four resistors representing the strain gauges, joined together in a diamond shape.
This type of output signal is produced by a wheatstone bridge strain gauge transducer which converts imbalance in bridge resistance generated by an applied force / load to a voltage drop between two opposite corners of the Wheatstone bridge circuit.
For a given fixed force, load or pressure, the voltage drop across two opposite corners of the circuit will is linearly proportional to the voltage supplied between the other two corners of the circuit. In a circuit diagram the wheatstone bridge is usually shown as four resistors representing the strain gauges, joined together in a diamond shape.
How to Connect a 4-20mA Current Loop Pressure Transmitter
All devices connected to make up a 4 to 20 milliamp current loop are connected in series.
The devices that are typically connected together include:
The devices that are typically connected together include:
- Pressure Transmitter
- Input Device to accept the signal from the Pressure Transmitter such as a Programmable Logic Controller (PLC), Controller, Panel Meter, Analog to Digital Converter (ADC) or Signal Conditioning Unit (SCU)
- Sensor Power Supply to power the Pressure Transmitter such as a Programmable Power Supply unit, DC Power Supply Unit (PSU), AC/DC Voltage Regulated Transformer or a DC Battery
Using Data Logging Equipment to Record and Analyze Measurement Readings
The primary function of a data logger is to create a record of measurements over a period of time at preset intervals.
Datalogging is used to record measurement in many areas of research and industry such as material performance testing, environmental monitoring, quality auditing, scientific experimentation and design proofing.
The main advantage of recording measurements using a data recorder is that it eliminates the errors and time spent writing down or typing in measurement results.
Datalogging is used to record measurement in many areas of research and industry such as material performance testing, environmental monitoring, quality auditing, scientific experimentation and design proofing.
The main advantage of recording measurements using a data recorder is that it eliminates the errors and time spent writing down or typing in measurement results.
Symptons and Causes of Damage to Pressure Transducer Diaphragms
It is possible to view part of the diaphragm on most pressure transducers and some which are completely exposed such as flush diaphragms are particular vulnerable to mechanical damage.
The first sign of damage may not actually be that detectable to the eye, instead it may show up as a small zero setting offset on the output signal. In some cases the damage maybe so severe that the diaphragm has completely ruptured compromising pressure containment or it is touching an internal component causing mechanical interference or an electrical short/open circuit.
The first sign of damage may not actually be that detectable to the eye, instead it may show up as a small zero setting offset on the output signal. In some cases the damage maybe so severe that the diaphragm has completely ruptured compromising pressure containment or it is touching an internal component causing mechanical interference or an electrical short/open circuit.
Explanations for Measurement Accuracy Specifications
The way accuracy is defined for pressure instruments on technical data sheets can vary significantly across manufacturers and product types.
There are many contributing error factors which go into a total uncertainty calculation and the proportion contributed by each one will be different from one measurement technology to another.
There are many contributing error factors which go into a total uncertainty calculation and the proportion contributed by each one will be different from one measurement technology to another.
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